John Wayne Gacy. Timothy McVeigh. Jeffrey Dahmer. Ted Bundy. They had a number of common traits. All of them were men. All of them were murderers. All of them were found guilty. All of them have names that will live in infamy. But they share something else in common....

From their quiet kitchen nook, Mr. and Mrs. Caplin spent several consecutive days watching a young family move into the house behind their own. The elderly couple liked what they saw in their new neighbors; Mr. Caplin admired the younger family’s work ethic while Mrs....